Planet Ocean Underwater Hotel, Florida, United States

This hotel, which lies underneath the waters of Key West, will have 12 aqua pods some 28 feet beneath the surface. Guests will be able to view surrounding marine life from the comfort of their rooms, which come with luxury amenities. One of the main goals of this new holiday spot, reported to cost £13m, is to help restore coral reefs and find new ways to prevent further destruction of the planet through funding and implementing projects.